We read the marketing blurb for book recently that boldly stated: ‘Superfruits are the product of a strategy, not something you find growing on a tree.’ So, we have asked dietitian and nutritionist Catherine Saxelby to put some of those much touted ‘superfoods’ incuding ‘superfruits’ under the spotlight for GI News readers in the coming months and report on how ‘miraculous’ or ‘super’ they really are.
Goji (wolfberry) is the latest ‘superfood’ to attract health-food evangelists and multi-level marketers. Small, pink-red, dried and a little like a sultana without the sweetness, you hear all sorts of claims – high antioxidant concentration to help fight everything from premature aging to chronic disease (heart disease, Alzheimers) and boosting your immune system, energy and metabolism. It’s hard to know whether it’s true or just marketing overkill. Reliable independent nutrition information on goji is hard to source – even what you see on pack varies wildly – so what follows are only average figures. If you add a tablespoon (10 g or 15 dried goji) to your cereal and you’ll add 30 calories, around 1 g protein, a little fat and 6 g carbohydrate. Compared with dried fruits like sultanas or cranberries, they have more protein (due to their tiny seeds), a little fat and a much lower sugar content which explains the taste.
Antioxidants and vitamins: Goji have a high nutrient density – in other words, they pack in a lot of vitamins and antioxidants. But again not a lot of analyses have been done by reputable sources. You’d expect them to be rich in vitamin C, fibre and antioxidants with their many anti-ageing effects. And you’d expect to find small amounts of many essential minerals, such as potassium, iron, magnesium and phosphorus. What we don’t accept is the hype about “500 times more vitamin C than orange juice” or “more protein than whole wheat” which is simply not true – goji may be on a par but not that much more.
Goji are being promoted as having the “highest antioxidant concentration of any fruit or vegetable” and “an antioxidant rating more than 10 times that of blueberries”. Antioxidant levels will depend on how fresh the goji were when tested and which antioxidant test was used. Some tests put tea at the top as the highest in antioxidants, others put blueberries at the top. You can’t compare them – they measure different things.
Most of the medical claims about goji are difficult if not impossible to substantiate. While there are more than 70 published studies on goji and health, most are animal trials. So it’s hard to give an accurate opinion about their role in cancer or heart problems. I haven’t seen a human clinical trial published in peer-reviewed journals. Maybe there’s some coming out soon which would be helpful.
Unique polysaccharides: Then there’s the ‘four unique polysaccharides’ in goji which marketing material harps on about. No-one knows much about these but they are a major constituent – around 50% – of goji. Polysaccharides are a form of carbohydrate. Most – like the starch in potato – are digested in the body; some pass through like fibre. There's nothing miraculous about this even if they are ‘unique’.
The take-home messages
- Basically, goji is an over-priced superfood that’s getting lots of hype and helping health food stores do good business. You can get goji’s nutrients from other foods much more cheaply.
- Eat them if you like them and don’t mind paying their hefty price. If you prefer the juice, be aware that it is usually a blend of 10% goji with apple or grape juice concentrate. This not only improves the taste, it adds sugar – between 10 and 13% – the same as in a soft drink! So read the list of ingredients and make sure you check how much sugar you are going to get in a glass before you part with your money.
- As for the miracle claims – that’s what they are: claims. No single food can cure cancer, enhance male sexual performance or halt Alzheimer’s disease.
Catherine Saxelby is the author of Zest and Nutrition for Life available online.